110 



tern F -\~ F' -\- G, at the riglit of and above this branch exist tlie 

 three other systems. 



If the point x is situated on the branch NS the reaction will still 

 be the same, but A W and A V are both positive. Hence, we find 

 the system F -\- F' -\- (t at the left of and above branch NS, the 

 three other systems at the right of and below this branch. 



If the })oint ,r gets on the branch SI) a quite different reaction, 

 namely F -\- F' "^ L -^ G takes place; in this reactton A I^ and 

 A IF are both positive. From this we deduce : at the left of and above 

 brauch DS we find the systems i^' + 7'^' -f /> and 7^' + F' + 6-' ; 

 at the right of and below this branch we find the two other systems. 



If the {)oint x gets on the brauch DR the reaction again changes 

 and becomes F -\- F' -\- Lt^G (see the last reaction of series A^) ; 

 AV and LW are both positive. From this we deduce: at the left 

 of and above brauch DR we find the system F -\- F' -{- L, at the 

 right of and below this brauch the three other systems. 



Above we have deduced the situation of the four three-phase 

 systems in regard to the curve LSDR in the assumption that the 

 four-phase equilibrium lielongs to type 1 -. if, however, the system 

 appertains to one of the other lypes 2 — 12 the situation may be 

 found in the same manner. 



When the four-phase equilibrium traverses the curve LSDR 

 (fig. 4) one of the following three-phase reactions will occur in 

 definite points. 



a)F-^F':^L ■ F':^F^L ; F-^F'-^L 



h)F^G':^G ; F':^F-^G ; F:^F'-^G 



c)F:^L^G ; F ^ L:^G ■ F^Gt;L 



il)F':^L-^G ; F'^L:^G ; F'-{-(;-;tL. 



In each of the reaction series 1 — 6 are found two of these three- 

 phase reactions ; in each of the series 7 — 10 three, and in each of 

 the series 11 — 12 four of the same. The last two of the group c 

 and (I can only take place wdien the four-phase equilibi'ium moves 

 away further from the point >,S or from F). 



Previously we already found : 



If in the four-phase equilil»rium a reacfion of group a takes place 

 it finds itself in the miniuium melting or conversion meltings point 

 of the complex F -\- F' ; in a 7^, 7 -diagram the four-phase curve 

 then meets the meliing point curve or the conversion curve of the 

 complex F + F' (Point /S in fig. 4). 



If in the four-phase equilibrium appears a reaction of group h it 

 finds itself in the maximum sublimation or conversion subhmation 



